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Cornelius V, Droessler L, Amasheh S. Quercetin Improves Barrier Properties in Porcine Small Intestine but Not in Peyer's Patches. Int J Mol Sci 2024; 25:1530. [PMID: 38338808 PMCID: PMC10855467 DOI: 10.3390/ijms25031530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/18/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
Peyer's patches (PPs) are part of the gut-associated lymphatic tissue (GALT) and represent the first line of the intestinal immunological defense. They consist of follicles with lymphocytes and an overlying subepithelial dome with dendritic cells and macrophages, and they are covered by the follicle-associated epithelium (FAE). A sealed paracellular pathway in the FAE is crucial for the controlled uptake of luminal antigens. Quercetin is the most abundant plant flavonoid and has a barrier-strengthening effect on tight junctions (TJs), a protein complex that regulates the paracellular pathway. In this study, we aimed to analyze the effect of quercetin on porcine PPs and the surrounding villus epithelium (VE). We incubated both tissue types for 4 h in Ussing chambers, recorded the transepithelial electrical resistance (TEER), and measured the unidirectional tracer flux of [3H]-mannitol. Subsequently, we analyzed the expression, protein amount, and localization of three TJ proteins, claudin 1, claudin 2, and claudin 4. In the PPs, we could not detect an effect of quercetin after 4 h, neither on TEER nor on the [3H]-mannitol flux. In the VE, quercetin led to a higher TEER value, while the [3H]-mannitol flux was unchanged. The pore-forming claudin 2 was decreased while the barrier-forming claudin 4 was increased and the expression was upregulated. Claudin 1 was unchanged and all claudins could be located in the paracellular membrane by immunofluorescence microscopy. Our study shows the barrier-strengthening effect of quercetin in porcine VE by claudin 4 upregulation and a claudin 2 decrease. Moreover, it underlines the different barrier properties of PPs compared to the VE.
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Affiliation(s)
| | | | - Salah Amasheh
- Institute of Veterinary Physiology, School of Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany
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Vitamin D Receptor Influences Intestinal Barriers in Health and Disease. Cells 2022; 11:cells11071129. [PMID: 35406694 PMCID: PMC8997406 DOI: 10.3390/cells11071129] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 12/12/2022] Open
Abstract
Vitamin D receptor (VDR) executes most of the biological functions of vitamin D. Beyond this, VDR is a transcriptional factor regulating the expression levels of many target genes, such as genes for tight junction proteins claudin-2, -5, -12, and -15. In this review, we discuss the progress of research on VDR that influences intestinal barriers in health and disease. We searched PubMed and Google Scholar using key words vitamin D, VDR, tight junctions, cancer, inflammation, and infection. We summarize the literature and progress reports on VDR regulation of tight junction distribution, cellular functions, and mechanisms (directly or indirectly). We review the impacts of VDR on barriers in various diseases, e.g., colon cancer, infection, inflammatory bowel disease, and chronic inflammatory lung diseases. We also discuss the limits of current studies and future directions. Deeper understanding of the mechanisms by which the VDR signaling regulates intestinal barrier functions allow us to develop efficient and effective therapeutic strategies based on levels of tight junction proteins and vitamin D/VDR statuses for human diseases.
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Rawat M, Nighot M, Al-Sadi R, Gupta Y, Viszwapriya D, Yochum G, Koltun W, Ma TY. IL1B Increases Intestinal Tight Junction Permeability by Up-regulation of MIR200C-3p, Which Degrades Occludin mRNA. Gastroenterology 2020; 159:1375-1389. [PMID: 32569770 DOI: 10.1053/j.gastro.2020.06.038] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 05/28/2020] [Accepted: 06/17/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND & AIMS Defects in the epithelial tight junction (TJ) barrier contribute to development of intestinal inflammation associated with diseases. Interleukin 1 beta (IL1B) increases intestinal permeability in mice. We investigated microRNAs that are regulated by IL1B and their effects on expression of TJ proteins and intestinal permeability. METHODS We used Targetscan to identify microRNAs that would bind the 3' untranslated region (3'UTR) of occludin mRNA; regions that interacted with microRNAs were predicted using the V-fold server and Assemble2, and 3-dimensional models were created using UCSF Chimera linked with Assemble2. Caco-2 cells were transfected with vectors that express microRNAs, analyzed by immunoblots and real-time polymerase chain reaction (PCR), and grown as monolayers; permeability in response to IL1B was assessed with the marker inulin. Male C57BL/6 mice were given intraperitoneal injections of IL1B and intestinal recycling perfusion was measured; some mice were given dextran sodium sulfate to induce colitis and/or gavage with an antagonist to MIR200C-3p (antagomiR-200C) or the nonspecific antagomiR (control). Intestinal tissues were collected from mice and analyzed by histology and real-time PCR; enterocytes were isolated by laser capture microdissection. We also analyzed colon tissues and organoids from patients with and without ulcerative colitis. RESULTS Incubation of Caco-2 monolayers with IL1B increased TJ permeability and reduced levels of occludin protein and mRNA without affecting the expression of other transmembrane TJ proteins. Targetscan identified MIR122, MIR200B-3p, and MIR200C-3p, as miRNAs that might bind to the occludin 3'UTR. MIR200C-3p was rapidly increased in Caco-2 cells incubated with IL1B; the antagomiR-200c prevented the IL1B-induced decrease in occludin mRNA and protein and reduced TJ permeability. Administration of IL1B to mice increased small intestinal TJ permeability, compared with mice given vehicle; enterocytes isolated from mice given IL1B had increased expression of MIR200C-3p and decreased levels of occludin messenger RNA (mRNA) and protein. Intestinal tissues from mice with colitis had increased levels of IL1B mRNA and MIR200C-3p and decreased levels of occludin mRNA; gavage of mice with antagomiR-200C reduced levels of MIR200C-3p and prevented the decrease in occludin mRNA and the increase in colonic permeability. Colon tissues and organoids from patients with ulcerative colitis had increased levels of IL1B mRNA and MIR200C-3p compared with healthy controls. Using 3-dimensional molecular modeling and mutational analyses, we identified the nucleotide bases in the occluding mRNA 3'UTR that interact with MIR200C-3p. CONCLUSIONS Intestine tissues from patients with ulcerative colitis and mice with colitis have increased levels of IL1B mRNA and MIR200C-3p, which reduces expression of occludin by enterocytes and thereby increases TJ permeability. Three-dimensional modeling of the interaction between MIR200C-3p and the occludin mRNA 3'UTR identified sites of interaction. The antagomiR-200C prevents the decrease in occludin in enterocytes and intestine tissues of mice with colitis, maintaining the TJ barrier.
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Affiliation(s)
- Manmeet Rawat
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Meghali Nighot
- Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Rana Al-Sadi
- Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania
| | - Yash Gupta
- Department of Medicine, Loyola University Medical Center, Maywood, Illinois
| | | | - Gregory Yochum
- Division of Colon and Rectal Surgery, Department of Surgery, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania; Department of Biochemistry and Molecular Biology, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
| | - Walter Koltun
- Division of Colon and Rectal Surgery, Department of Surgery, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
| | - Thomas Y Ma
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico; Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania.
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Urban F, Hajek K, Naber T, Anczykowski B, Schäfer M, Wegener J. P ETER-assay: Combined Impedimetric Detection of Permeability (P E) and Resistance (TER) of Barrier-Forming Cell Layers. Sci Rep 2020; 10:7373. [PMID: 32355192 PMCID: PMC7192940 DOI: 10.1038/s41598-020-63624-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 12/05/2019] [Indexed: 11/09/2022] Open
Abstract
Epithelial and endothelial barrier function is typically studied in vitro by growing the cells of interest on permeable supports that are sandwiched between two fluid compartments. This setup mimics the physiological situation with the cell layer as the diffusion barrier at the interface between two chemically distinct fluids. Routinely, the barrier function is quantitatively described by two key parameters: (i) the transepithelial or transendothelial electrical resistance (TER) as a measure of the permeability for small inorganic ions and (ii) the permeability coefficient (PE) as a descriptor of the permeability for molecular tracers. So far the two parameters have been determined in separate experiments. This study introduces a device that allows for simultaneous detection of PE and TER of the very same cell monolayer in one single experiment (PETER-assay). The novel approach is entirely based on AC impedance measurements in two different modes, so that TER and PE become available in real time. The new approach is demonstrated for three epithelial cell lines derived from the kidney (MDCK-I, MDCK-II, NRK) with very different barrier properties under stationary conditions and when challenged by barrier-breaking fungal toxin cytochalasin D. PETER provides an excellent time-resolution and completely automated data collection.
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Affiliation(s)
- Florian Urban
- Universitaet Regensburg, Institut fuer Analytische Chemie, Chemo- & Biosensorik, Universitaetsstr. 31, 93053, Regensburg (G), Germany
| | - Kathrin Hajek
- Universitaet Regensburg, Institut fuer Analytische Chemie, Chemo- & Biosensorik, Universitaetsstr. 31, 93053, Regensburg (G), Germany
| | - Tobias Naber
- Universitaet Regensburg, Institut fuer Analytische Chemie, Chemo- & Biosensorik, Universitaetsstr. 31, 93053, Regensburg (G), Germany
| | | | - Marcus Schäfer
- nanoAnalytics GmbH, Heisenbergstr. 11, 48149, Münster (G), Germany
| | - Joachim Wegener
- Universitaet Regensburg, Institut fuer Analytische Chemie, Chemo- & Biosensorik, Universitaetsstr. 31, 93053, Regensburg (G), Germany. .,Fraunhofer Research Institution for Microsystems and Solid State Technologies EMFT, 80686, Muenchen (G), Germany.
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Sayoc-Becerra A, Krishnan M, Fan S, Jimenez J, Hernandez R, Gibson K, Preciado R, Butt G, McCole DF. The JAK-Inhibitor Tofacitinib Rescues Human Intestinal Epithelial Cells and Colonoids from Cytokine-Induced Barrier Dysfunction. Inflamm Bowel Dis 2020; 26:407-422. [PMID: 31751457 PMCID: PMC7012302 DOI: 10.1093/ibd/izz266] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Alterations to epithelial tight junctions can compromise the ability of the epithelium to act as a barrier between luminal contents and the underlying tissues, thereby increasing intestinal permeability, an early critical event in inflammatory bowel disease (IBD). Tofacitinib (Xeljanz), an orally administered pan-Janus kinase (JAK) inhibitor, was recently approved for the treatment of moderate to severe ulcerative colitis. Nevertheless, the effects of tofacitinib on intestinal epithelial cell functions are largely unknown. The aim of this study was to determine if JAK inhibition by tofacitinib can rescue cytokine-induced barrier dysfunction in intestinal epithelial cells (IECs). METHODS T84 IECs were used to evaluate the effects of tofacitinib on JAK-signal transducer and activator of transcription (STAT) activation, barrier permeability, and expression and localization of tight junction proteins. The impact of tofacitinib on claudin-2 promoter activity was assessed in HT-29 IECs. Tofacitinib rescue of barrier function was also tested in human colonic stem cell-derived organoids. RESULTS Pretreatment with tofacitinib prevented IFN-γ-induced decreases in transepithelial electrical resistance (TER) and increases in 4 kDa FITC-dextran permeability (FD4), partly due to claudin-2 transcriptional regulation and restriction of ZO-1 rearrangement at tight junctions. Although tofacitinib administered after IFN-γ challenge only partially normalized TER and claudin-2 levels, FD4 permeability and ZO-1 localization were fully recovered. The IFN-γ-induced FD4 permeability in primary human colonoids was fully rescued by tofacitinib. CONCLUSIONS These data suggest differential therapeutic efficacy of tofacitinib in the rescue of pore vs leak-tight junction barrier defects and indicate a potential contribution of improved epithelial barrier function to the beneficial effects of tofacitinib in IBD patients.
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Affiliation(s)
- Anica Sayoc-Becerra
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Moorthy Krishnan
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Shujun Fan
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Jossue Jimenez
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Rebecca Hernandez
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Kyle Gibson
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Reyna Preciado
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA
| | - Grant Butt
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Declan F McCole
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA,Address correspondence to: Declan F. McCole, PhD, Division of Biomedical Sciences, School of Medicine, University of California–Riverside, 307 School of Medicine Research Building, 900 University Avenue, Riverside, CA, 92521 USA. E-mail:
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6
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Tervonen A, Ihalainen TO, Nymark S, Hyttinen J. Structural dynamics of tight junctions modulate the properties of the epithelial barrier. PLoS One 2019; 14:e0214876. [PMID: 30964903 PMCID: PMC6456171 DOI: 10.1371/journal.pone.0214876] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/21/2019] [Indexed: 01/09/2023] Open
Abstract
Tight junctions are dynamic structures that are crucial in establishing the diffusion and electrical barrier of epithelial monolayers. Dysfunctions in the tight junctions can impede this barrier function and lead to many pathological conditions. Unfortunately, detailed understanding of the non-specific permeation pathway through the tight junctions, the so-called leak pathway, is lacking. We created computational models of the leak pathway to describe the two main barrier measures, molecular permeability and transepithelial electric resistance while using common structural dynamics. Our results showed that the proposed alternatives for the leak pathway, the bicellular strand opening dynamics and the tricellular pores, contribute together with distinct degrees, depending on the epithelium. The models can also capture changes in the tight junction barrier caused by changes in tight junction protein composition. In addition, we observed that the molecular permeability was markedly more sensitive to changes in the tight junction structure and strand dynamics compared with transepithelial electric resistance. The results highlight that our model creates a good methodological framework to integrate knowledge on the tight junction structure as well as to provide insights and tools to advance tight junction research.
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Affiliation(s)
- Aapo Tervonen
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, Tampere, Finland
- * E-mail:
| | - Teemu O. Ihalainen
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, Tampere, Finland
| | - Soile Nymark
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, Tampere, Finland
| | - Jari Hyttinen
- Faculty of Medicine and Health Technology and BioMediTech Institute, Tampere University, Tampere, Finland
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Zhang YG, Lu R, Xia Y, Zhou D, Petrof E, Claud EC, Sun J. Lack of Vitamin D Receptor Leads to Hyperfunction of Claudin-2 in Intestinal Inflammatory Responses. Inflamm Bowel Dis 2019; 25:97-110. [PMID: 30289450 PMCID: PMC6290786 DOI: 10.1093/ibd/izy292] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Indexed: 12/16/2022]
Abstract
BACKGROUND Vitamin D3 and vitamin D receptor (VDR) are involved in the pathogenesis of inflammatory bowel disease (IBD) and bacterial infection. Claudin-2 is a junction protein that mediates paracellular water transport in epithelia. Elevation of Claudin-2 is associated with active IBD. However, VDR involved in epithelial junctions under inflammation and infection remains largely unknown. We investigated the mechanisms on how VDR and Claudin-2 are related in inflamed states. METHODS Using cultured VDR-/- enteroids, human intestinal epithelial cells, VDR-/- mice with Salmonella- or DSS-colitis, and human IBD samples, we investigated the mechanisms how VDR and Claudin-2 are related in inflamed states. RESULTS After Salmonella infection had taken place, we observed significantly enhanced Claudin-2 and an increased bacterial invasion and translocation. A lack of VDR regulation led to a robust increase of Claudin-2 at the mRNA and protein levels post-infection. In DSS-treated VDR-/- mice, Claudin-2 was significantly increased. Location and quantification of Claudin-2 protein in the mouse colons treated with DSS also confirmed these results. Inflammatory cytokines were significantly higher in the serum and mRNA levels in intestine, which are known to increase Claudin-2. Furthermore, in inflamed intestine of ulcerative colitis patients, VDR expression was low and Claudin-2 was enhanced. Mechanistically, we identified the enhanced Claudin-2 promoter activity through the binding sites of NF-κB and STAT in inflamed VDR-/- cells. CONCLUSIONS Our studies have identified a new role for intestinal epithelial VDR in regulating barrier functions in the context of infection and inflammation.
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Affiliation(s)
- Yong-guo Zhang
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Rong Lu
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Yinglin Xia
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - David Zhou
- Department of Pathology, University of Rochester, Rochester, New York, USA,Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Elaine Petrof
- Department of Medicine, GI Diseases Research Unit and Division of Infectious Diseases, Queen’s University, Kingston, Ontario, Canada
| | - Erika C Claud
- Department of Pediatrics and Medicine, The University of Chicago, Chicago, Illinois, USA
| | - Jun Sun
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA,Address correspondence to: Jun Sun, PhD, AGA Fellow, Professor Division of Gastroenterology and Hepatology Department of Medicine, University of Illinois at Chicago 840 S. Wood Street, Room 704 CSB, MC716 Chicago, IL, 60612, USA. E-mail:
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Zhang C, Yan J, Xiao Y, Shen Y, Wang J, Ge W, Chen Y. Inhibition of Autophagic Degradation Process Contributes to Claudin-2 Expression Increase and Epithelial Tight Junction Dysfunction in TNF-α Treated Cell Monolayers. Int J Mol Sci 2017; 18:ijms18010157. [PMID: 28106723 PMCID: PMC5297790 DOI: 10.3390/ijms18010157] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/01/2017] [Accepted: 01/10/2017] [Indexed: 02/06/2023] Open
Abstract
Tight junction dysfunction plays a vital role in some chronic inflammatory diseases. Pro-inflammatory cytokines, especially tumor necrosis factor alpha (TNF-α), act as important factors in intestinal epithelial tight junction dysfunction during inflammatory conditions. Autophagy has also been shown to be crucial in tight junction function and claudin-2 expression, but whether autophagy has an effect on the change of claudin-2 expression and tight junction function induced by TNF-α is still unknown. To answer this question, we examined the expression of claudin-2 protein, transepithelial electrical resistance (TER), and permeability of cell monolayers, autophagy flux change, and lysosomal pH after TNF-α with or without PP242 treatment. Our study showed that claudin-2 expression, intestinal permeability, microtubule-associated protein 1 light chain 3B II (LC3B-II) and sequestosome 1 (P62) expression largely increased while TER values decreased in TNF-α treated cell monolayers. Further research using 3-methyladenine (3-MA), bafilomycin A1, and ad-mCherry-GFP-LC3B adenovirus demonstrated that LC3B-II increase induced by TNF-α was attributed to the inhibition of autophagic degradation. Moreover, both qualitative and quantitative method confirmed the increase of lysosomal pH, and mammalian target of rapamycin (mTOR) inhibitor PP242 treatment relieved this elevation. Moreover, PP242 treatment also alleviated the change of autophagy flux, TER, and claudin-2 expression induced by TNF-α. Therefore, we conclude that increase of claudin-2 levels and intestinal epithelial tight junction dysfunction are partly caused by the inhibition of autophagic degradation in TNF-α treated cell monolayers.
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Affiliation(s)
- Cong Zhang
- Department of Gastroenterology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
| | - Junkai Yan
- Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai Institute for Pediatric Research, Shanghai 200092, China.
| | - Yongtao Xiao
- Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai Institute for Pediatric Research, Shanghai 200092, China.
| | - Yujie Shen
- Department of Gastroenterology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
| | - Jiazheng Wang
- Department of Gastroenterology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
| | - Wensong Ge
- Department of Gastroenterology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
| | - Yingwei Chen
- Department of Gastroenterology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
- Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai Institute for Pediatric Research, Shanghai 200092, China.
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Price ER, Brun A, Caviedes-Vidal E, Karasov WH. Digestive adaptations of aerial lifestyles. Physiology (Bethesda) 2015; 30:69-78. [PMID: 25559157 DOI: 10.1152/physiol.00020.2014] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Flying vertebrates (birds and bats) are under selective pressure to reduce the size of the gut and the mass of the digesta it carries. Compared with similar-sized nonflying mammals, birds and bats have smaller intestines and shorter retention times. We review evidence that birds and bats have lower spare digestive capacity and partially compensate for smaller intestines with increased paracellular nutrient absorption.
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Affiliation(s)
- Edwin R Price
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin;
| | - Antonio Brun
- Laboratorio de Biología Integrativa, Instituto Multidisciplinario de Investigaciones Biológicas de San Luis, Consejo Nacional de Investigaciones Científicas y Técnicas, San Luis, Argentina; and
| | - Enrique Caviedes-Vidal
- Laboratorio de Biología Integrativa, Instituto Multidisciplinario de Investigaciones Biológicas de San Luis, Consejo Nacional de Investigaciones Científicas y Técnicas, San Luis, Argentina; and Departamento de Bioquímica y Ciencias Biológicas y Laboratorio de Biología "Professor E. Caviedes Codelia," Universidad Nacional de San Luis, San Luis, Argentina
| | - William H Karasov
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin
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10
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Zhang YG, Wu S, Lu R, Zhou D, Zhou J, Carmeliet G, Petrof E, Claud EC, Sun J. Tight junction CLDN2 gene is a direct target of the vitamin D receptor. Sci Rep 2015. [PMID: 26212084 PMCID: PMC4650691 DOI: 10.1038/srep10642] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The breakdown of the intestinal barrier is a common manifestation of many diseases. Recent evidence suggests that vitamin D and its receptor VDR may regulate intestinal barrier function. Claudin-2 is a tight junction protein that mediates paracellular water transport in intestinal epithelia, rendering them “leaky”. Using whole body VDR-/- mice, intestinal epithelial VDR conditional knockout (VDRΔIEC) mice, and cultured human intestinal epithelial cells, we demonstrate here that the CLDN2 gene is a direct target of the transcription factor VDR. The Caudal-Related Homeobox (Cdx) protein family is a group of the transcription factor proteins which bind to DNA to regulate the expression of genes. Our data showed that VDR-enhances Claudin-2 promoter activity in a Cdx1 binding site-dependent manner. We further identify a functional vitamin D response element (VDRE) 5΄-AGATAACAAAGGTCA-3΄ in the Cdx1 site of the Claudin-2 promoter. It is a VDRE required for the regulation of Claudin-2 by vitamin D. Absence of VDR decreased Claudin-2 expression by abolishing VDR/promoter binding. In vivo, VDR deletion in intestinal epithelial cells led to significant decreased Claudin-2 in VDR-/- and VDRΔIEC mice. The current study reveals an important and novel mechanism for VDR by regulation of epithelial barriers.
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Affiliation(s)
- Yong-guo Zhang
- Department of Biochemistry, Rush University, Chicago, Illinois, USA
| | - Shaoping Wu
- Department of Biochemistry, Rush University, Chicago, Illinois, USA
| | - Rong Lu
- Department of Biochemistry, Rush University, Chicago, Illinois, USA
| | - David Zhou
- Department of Pathology, University of Rochester, Rochester, New York, USA
| | - Jingsong Zhou
- Department of Physiology, Kansas City University of Medicine and Bioscience, Kansas City, Missouri, USA
| | - Geert Carmeliet
- Lab of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Elaine Petrof
- Department of Medicine, GI Diseases Research Unit and Division of Infectious Diseases, Queen's University, Ontario, Canada
| | - Erika C Claud
- Departments of Pediatrics and Medicine, The University of Chicago Medical Center, Chicago, Illinois, USA
| | - Jun Sun
- 1] Department of Biochemistry, Rush University, Chicago, Illinois, USA [2] Department of Pathology, University of Rochester, Rochester, New York, USA
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Nomme J, Antanasijevic A, Caffrey M, Van Itallie CM, Anderson JM, Fanning AS, Lavie A. Structural Basis of a Key Factor Regulating the Affinity between the Zonula Occludens First PDZ Domain and Claudins. J Biol Chem 2015; 290:16595-606. [PMID: 26023235 DOI: 10.1074/jbc.m115.646695] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Indexed: 11/06/2022] Open
Abstract
The molecular seal between epithelial cells, called the tight junction (TJ), is built by several membrane proteins, with claudins playing the most prominent role. The scaffold proteins of the zonula occludens family are required for the correct localization of claudins and hence formation of the TJ. The intracellular C terminus of claudins binds to the N-terminal PDZ domain of zonula occludens proteins (PDZ1). Of the 23 identified human claudin proteins, nine possess a tyrosine at the -6 position. Here we show that the claudin affinity for PDZ1 is dependent on the presence or absence of this tyrosine and that the affinity is reduced if the tyrosine is modified by phosphorylation. The PDZ1 β2-β3 loop undergoes a significant conformational change to accommodate this tyrosine. Cell culture experiments support a regulatory role for this tyrosine. Plasticity has been recognized as a critical property of TJs that allow cell remodeling and migration. Our work provides a molecular framework for how TJ plasticity may be regulated.
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Affiliation(s)
- Julian Nomme
- From the Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607
| | - Aleksandar Antanasijevic
- From the Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607
| | - Michael Caffrey
- From the Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607
| | - Christina M Van Itallie
- Laboratory of Tight Junction Structure and Function, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | - James M Anderson
- Laboratory of Tight Junction Structure and Function, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Alan S Fanning
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Arnon Lavie
- From the Department of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607,
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12
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Pathways and progress in improving drug delivery through the intestinal mucosa and blood-brain barriers. Ther Deliv 2015; 5:1143-63. [PMID: 25418271 DOI: 10.4155/tde.14.67] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
One of the major hurdles in developing therapeutic agents is the difficulty in delivering drugs through the intestinal mucosa and blood-brain barriers (BBB). The goal here is to describe the general structures of the biological barriers and the strategies to enhance drug delivery across these barriers. Prodrug methods used to improve drug penetration via the transcellular pathway have been successfully developed, and some prodrugs have been used to treat patients. The use of transporters to improve absorption of some drugs (e.g., antiviral agents) has also been successful in treating patients. Other methods, including blocking the efflux pumps to improve transcellular delivery, and modulation of cell-cell adhesion in the intercellular junctions to improve paracellular delivery across biological barriers, are still in the investigational stage.
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13
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Claudin-3 and occludin tissue content in the glands of colonic mucosa with and without a fecal stream. J Mol Histol 2015; 46:183-94. [PMID: 25649016 DOI: 10.1007/s10735-015-9610-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/28/2015] [Indexed: 02/07/2023]
Abstract
The synthesis of the proteins of the apical tight junctions (TJs) depends on a continuous supply of short-chain fatty acids (SCFAs) in colonic epithelium. No studies have evaluated the tissue contents of the TJs proteins in colon segments devoid of a fecal stream. To evaluate the contents of claudin-3 and occludin in the glands of colonic mucosa devoid of a fecal stream. Forty-five rats underwent a diversion of the fecal stream via a left side colostomy and distal mucous fistula. Three groups of 15 animals each were sacrificed at 6, 12 or 18 weeks after surgery. The presence and severity of colitis were defined by histology and inflammation grading scales, respectively. The expression of claudin-3 and occludin were evaluated by immunohistochemistry, and their contents were evaluated by computer-assisted image analysis. Mann-Whitney and Kruskal-Wallis tests were used to evaluate the results at a significance level of 5% (p < 0.05). The colonic epithelium without a fecal stream had a higher degree of inflammation. Colonic glands without a fecal stream showed a reduction in claudin-3 content independent of the time and reduction in occludin content after 12 weeks of intestinal exclusion. The content of claudin-3 and occludin were mainly reduced at the apical surfaces of the colon glands, whereas segments retaining the fecal stream were maintained. The content of claudin-3 was not reduced with time, although the levels of occludin were reduced after 6 weeks and did not vary thereafter. Deficiencies in SCFAs decreased the content of claudin-3 and occludin in colonic glands with the areas of worst inflammation, confirming the importance of an adequate supply of SCFAs in maintaining the integrity of TJ proteins.
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14
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Nighot PK, Hu CAA, Ma TY. Autophagy enhances intestinal epithelial tight junction barrier function by targeting claudin-2 protein degradation. J Biol Chem 2015; 290:7234-46. [PMID: 25616664 DOI: 10.1074/jbc.m114.597492] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Autophagy is an intracellular degradation pathway and is considered to be an essential cell survival mechanism. Defects in autophagy are implicated in many pathological processes, including inflammatory bowel disease. Among the innate defense mechanisms of intestinal mucosa, a defective tight junction (TJ) barrier has been postulated as a key pathogenic factor in the causation and progression of inflammatory bowel disease by allowing increased antigenic permeation. The cross-talk between autophagy and the TJ barrier has not yet been described. In this study, we present the novel finding that autophagy enhances TJ barrier function in Caco-2 intestinal epithelial cells. Nutrient starvation-induced autophagy significantly increased transepithelial electrical resistance and reduced the ratio of sodium/chloride paracellular permeability. Nutrient starvation reduced the paracellular permeability of small-sized urea but not larger molecules. The role of autophagy in the modulation of paracellular permeability was confirmed by pharmacological induction as well as pharmacological and genetic inhibition of autophagy. Consistent with the autophagy-induced reduction in paracellular permeability, a marked decrease in the level of the cation-selective, pore-forming TJ protein claudin-2 was observed after cell starvation. Starvation reduced the membrane presence of claudin-2 and increased its cytoplasmic, lysosomal localization. Therefore, our data show that autophagy selectively reduces epithelial TJ permeability of ions and small molecules by lysosomal degradation of the TJ protein claudin-2.
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Affiliation(s)
| | - Chien-An Andy Hu
- Biochemistry and Molecular Biology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131 and
| | - Thomas Y Ma
- From the Departments of Internal Medicine and the Veterans Affairs Medical Center, Albuquerque, New Mexico 87108
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15
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Goswami P, Das P, Verma AK, Prakash S, Das TK, Nag TC, Ahuja V, Gupta SD, Makharia GK. Are alterations of tight junctions at molecular and ultrastructural level different in duodenal biopsies of patients with celiac disease and Crohn's disease? Virchows Arch 2014; 465:521-30. [PMID: 25240724 DOI: 10.1007/s00428-014-1651-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 08/24/2014] [Accepted: 08/26/2014] [Indexed: 12/16/2022]
Abstract
Abnormalities of transmembrane and cytoplasmic proteins of tight junctions (TJ) have been implicated in pathogenesis of both celiac (CeD) and Crohn's diseases (CD). Since disease pathogenesis in CeD and CD are different, we planned to study if there is any differential expression pattern of TJ marker proteins and ultrastructural changes, respectively, in duodenal villi vs crypts. Endoscopic duodenal biopsies from treatment naïve patients with CeD (n = 24), active CD (n = 28), and functional dyspepsia (as controls, n = 15), both at baseline and 6 months after treatment, were subjected to light microscopic analysis (modified Marsh grading); immune-histochemical staining and Western blot analysis to see the expression of key TJ proteins [trans-membrane proteins (claudin-2, claudin-3, claudin-4, occludin, and JAM) and cytoplasmic protein (ZO-1)]. Transmission electron microscopy and image analysis of the TJs were also performed. There was significant overexpression of claudin-2 (pore-forming) and occludin (protein maintaining cell polarity) with under-expression of claudin-3 and claudin-4 (pore-sealing proteins) in treatment naïve CeD and active CD with simultaneous alteration in ultrastructure of TJs such as loss of penta-laminar structure and TJ dilatation. Normalization of some of these TJ proteins was noted 6 months after treatment. These changes were not disease specific and were not different in duodenal villi and crypts. Overexpression of pore-forming and under-expression of pore-sealing TJ proteins lead to dilatation of TJ. These changes are neither disease specific nor site specific and the end result of mucosal inflammation.
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Affiliation(s)
- Pooja Goswami
- Department of Gastroenterology and Human Nutrition, All India institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
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16
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Christensen EI, Wagner CA, Kaissling B. Uriniferous tubule: structural and functional organization. Compr Physiol 2013; 2:805-61. [PMID: 23961562 DOI: 10.1002/cphy.c100073] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The uriniferous tubule is divided into the proximal tubule, the intermediate (thin) tubule, the distal tubule and the collecting duct. The present chapter is based on the chapters by Maunsbach and Christensen on the proximal tubule, and by Kaissling and Kriz on the distal tubule and collecting duct in the 1992 edition of the Handbook of Physiology, Renal Physiology. It describes the fine structure (light and electron microscopy) of the entire mammalian uriniferous tubule, mainly in rats, mice, and rabbits. The structural data are complemented by recent data on the location of the major transport- and transport-regulating proteins, revealed by morphological means(immunohistochemistry, immunofluorescence, and/or mRNA in situ hybridization). The structural differences along the uriniferous tubule strictly coincide with the distribution of the major luminal and basolateral transport proteins and receptors and both together provide the basis for the subdivision of the uriniferous tubule into functional subunits. Data on structural adaptation to defined functional changes in vivo and to genetical alterations of specified proteins involved in transepithelial transport importantly deepen our comprehension of the correlation of structure and function in the kidney, of the role of each segment or cell type in the overall renal function,and our understanding of renal pathophysiology.
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17
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Wu S, Yuan L, Zhang Y, Liu F, Li G, Wen K, Kocher J, Yang X, Sun J. Probiotic Lactobacillus rhamnosus GG mono-association suppresses human rotavirus-induced autophagy in the gnotobiotic piglet intestine. Gut Pathog 2013; 5:22. [PMID: 23924832 PMCID: PMC3750464 DOI: 10.1186/1757-4749-5-22] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Accepted: 07/25/2013] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Human rotavirus (HRV) is the most important cause of severe diarrhea in infants and young children. Probiotic Lactobacillus rhamnosus GG (LGG) reduces rotavirus infection and diarrhea. However, the molecular mechanisms of LGG-mediated protection from rotavirus infection are poorly understood. Autophagy plays an essential role in responses to microbial pathogens. However, the role of autophagy in HRV infection and LGG treatment is unknown. We hypothesize that rotavirus gastroenteritis activates autophagy and that LGG suppresses virus-induced autophagy and prevents intestinal damage in infected piglets. METHODS We used LGG feeding to combat viral gastroenteritis in the gnotobiotic pig model of virulent HRV infection. RESULTS We found that LGG feeding did not increase autophagy, whereas virus infection induced autophagy in the piglet intestine. Virus infection increased the protein levels of the autophagy markers ATG16L1 and Beclin-1 and the autophagy regulator mTOR. LGG treatment during viral gastroenteritis reduced autophagy marker expression to normal levels, induced apoptosis and partially prevented virus-induced tissue damage. CONCLUSION Our study provides new insights into virus-induced autophagy and LGG suppression of uncontrolled autophagy and intestinal injury. A better understanding of the antiviral activity of LGG will lead to novel therapeutic strategies for infant infectious diseases.
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Affiliation(s)
- Shaoping Wu
- Department of Biochemistry, Rush University, Cohn Research Building, 1735 W. Harrison Street, Chicago, IL 60612, USA
| | - Lijuan Yuan
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Yongguo Zhang
- Department of Biochemistry, Rush University, Cohn Research Building, 1735 W. Harrison Street, Chicago, IL 60612, USA
| | - Fangning Liu
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Guohua Li
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Ke Wen
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Jacob Kocher
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Xingdong Yang
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building, 1981 Kraft Dr, Blacksburg, VA 24061-0913, USA
| | - Jun Sun
- Department of Biochemistry, Rush University, Cohn Research Building, 1735 W. Harrison Street, Chicago, IL 60612, USA
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18
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Salmonella infection upregulates the leaky protein claudin-2 in intestinal epithelial cells. PLoS One 2013; 8:e58606. [PMID: 23505542 PMCID: PMC3594366 DOI: 10.1371/journal.pone.0058606] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/07/2013] [Indexed: 02/08/2023] Open
Abstract
Background Tight junctions seal the space between adjacent epithelial cells. Mounting evidence suggests that tight junction proteins play a key role in the pathogenesis of human disease. Claudin is a member of the tight junction protein family, which has 24 members in humans. To regulate cellular function, claudins interact structurally and functionally with membrane and scaffolding proteins via their cytoplasmic domain. In particular, claudin-2 is known to be a leaky protein that contributes to inflammatory bowel disease and colon cancer. However, the involvement of claudin-2 in bacterial infection in the intestine remains unknown. Methods/Principal Findings We hypothesized that Salmonella elevates the leaky protein claudin-2 for its own benefit to facilitate bacterial invasion in the colon. Using a Salmonella-colitis mouse model and cultured colonic epithelial cells, we found that pathogenic Salmonella colonization significantly increases the levels of claudin-2 protein and mRNA in the intestine, but not that of claudin-3 or claudin-7 in the colon, in a time-dependent manner. Immunostaining studies showed that the claudin-2 expression along the crypt-villous axis postinfection. In vitro, Salmonella stimulated claudin-2 expression in the human intestinal epithelial cell lines SKCO15 and HT29C19A. Further analysis by siRNA knockdown revealed that claudin-2 is associated with the Salmonella-induced elevation of cell permeability. Epithelial cells with claudin-2 knockdown had significantly less internalized Salmonella than control cells with normal claudin-2 expression. Inhibitor assays demonstrated that this regulation is mediated through activation of the EGFR pathway and the downstream protein JNK. Conclusion/Significance We have shown that Salmonella targets the tight junction protein claudin-2 to facilitate bacterial invasion. We speculate that this disruption of barrier function contributes to a new mechanism by which bacteria interact with their host cells and suggests the possibility of blocking claudin-2 as a potential therapeutic strategy to prevent bacterial invasion.
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19
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Abstract
Tissue barriers are critical in the pathogenesis of human diseases, such as atopic dermatitis, inflammatory bowel diseases and various cancers. Preserving or restoring barrier functions of the epithelia cells is a therapeutic strategy to prevent and treat the illness. Mounting evidence indicates that vitamin D and the vitamin D receptor (VDR) play key roles in the pathogenesis of human diseases. In particular, we note an interesting link between vitamin D/VDR signaling and tissue barriers. In the current review, we summarize the recent progress on vitamin D and cell junction complexes. We focus on the functions of VDR and VDR-associated intracellular junction proteins, such as β-catenin and claudins. We also discuss the potential therapeutic functions of vitamin D in treating defective tissue barriers that involve skin, intestine, lung, kidney and other organs. However, the mechanisms for the vitamin D/VDR signaling in tissue barriers remain largely unknown. Further studies on vitamin D/VDR’s multiple functions in physiological models will suggest new therapeutic targets for prevention and treatment diseases with defective barrier functions.
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Affiliation(s)
- Yong-Guo Zhang
- Department of Biochemistry, Rush University, 1735 W. Harrison Street, Chicago, IL, 60612, USA
| | - Shaoping Wu
- Department of Biochemistry, Rush University, 1735 W. Harrison Street, Chicago, IL, 60612, USA
| | - Jun Sun
- Department of Biochemistry, Rush University, 1735 W. Harrison Street, Chicago, IL, 60612, USA
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20
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Van Itallie CM, Tietgens AJ, LoGrande K, Aponte A, Gucek M, Anderson JM. Phosphorylation of claudin-2 on serine 208 promotes membrane retention and reduces trafficking to lysosomes. J Cell Sci 2012; 125:4902-12. [PMID: 22825868 DOI: 10.1242/jcs.111237] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Claudins are critical components of epithelial and endothelial tight junction seals, but their post-transcriptional regulation remains poorly understood. Several studies have implicated phosphorylation in control of claudin localisation and/or function, but these have focused on single sites or pathways with differing results, so that it has been difficult to draw general functional conclusions. In this study, we used mass spectrometry (MS) analysis of purified claudin-2 from MDCK II cells and found that the cytoplasmic tail is multiply phosphorylated on serines, a threonine and tyrosines. Phos-tag SDS PAGE revealed that one site, S208, is heavily constitutively phosphorylated in MDCK II cells and in mouse kidney; this site was targeted for further study. Mutational analysis revealed that the phosphomimetic mutant of claudin-2, S208E, was preferentially localised to the plasma membrane while claudin-2 S208A, which could not be phosphorylated at this site, both immunolocalized and co-fractionated with lysosomal markers. Mutations at sites that were previously reported to interfere with plasma membrane targeting of claudin-2 reduced phosphorylation at S208, suggesting that membrane localisation is required for phosphorylation; however phosphorylation at S208 did not affect binding to ZO-1 or ZO-2 Administration of forskolin or PGE2 resulted in dephosphorylation at S208 and transient small increases in transepithelial electrical resistance (TER). Together these data are consistent with phosphorylation at S208 playing a major role in the retention of claudin-2 at the plasma membrane.
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Affiliation(s)
- Christina M Van Itallie
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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21
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Ye D, Guo S, Al-Sadi R, Ma TY. MicroRNA regulation of intestinal epithelial tight junction permeability. Gastroenterology 2011; 141:1323-33. [PMID: 21763238 PMCID: PMC3724217 DOI: 10.1053/j.gastro.2011.07.005] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/13/2011] [Accepted: 07/06/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Defects in the intestinal epithelial tight junction (TJ) barrier contribute to intestinal inflammation. A tumor necrosis factor (TNF)-α-induced increase in intestinal TJ permeability contributes to the intestinal TJ barrier defect in inflammatory disorders. We investigated the mechanisms by which TNF-α induces occludin depletion and an increase in intestinal TJ permeability. METHODS We assessed intestinal TJ barrier function using intestinal epithelial model systems: filter-grown Caco-2 monolayers and recycling perfusion studies of mouse small intestine. RESULTS TNF-α caused a rapid increase in expression of microRNA (miR)-122a in enterocytes, cultured cells, and intestinal tissue. The overexpressed miR-122a bound to a binding motif at the 3'-untranslated region of occludin messenger RNA (mRNA) to induce its degradation; mRNA degradation depleted occludin from enterocytes, resulting in increased intestinal TJ permeability. Transfection of enterocytes with an antisense oligoribonucleotide against miR-122a blocked the TNF-α-induced increase in enterocyte expression of miR-122a, degradation of occludin mRNA, and increase in intestinal permeability. Overexpression of miR-122a in enterocytes using pre-miR-122a was sufficient to induce degradation of occludin mRNA and an increase in intestinal permeability. CONCLUSIONS TNF-α regulates intestinal permeability by inducing miR-122a-mediated degradation of occludin mRNA. These studies show the feasibility of therapeutically targeting miR-122a in vivo to preserve the intestinal barrier.
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Affiliation(s)
- Dongmei Ye
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Shuhong Guo
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Rana Al-Sadi
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico,Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico
| | - Thomas Y. Ma
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico,Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico
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22
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Raleigh DR, Boe DM, Yu D, Weber CR, Marchiando AM, Bradford EM, Wang Y, Wu L, Schneeberger EE, Shen L, Turner JR. Occludin S408 phosphorylation regulates tight junction protein interactions and barrier function. ACTA ACUST UNITED AC 2011; 193:565-82. [PMID: 21536752 PMCID: PMC3087007 DOI: 10.1083/jcb.201010065] [Citation(s) in RCA: 191] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Occludin S408 phosphorylation regulates interactions between occludin, ZO-1, and select claudins to define tight junction molecular structure and barrier function. Although the C-terminal cytoplasmic tail of the tight junction protein occludin is heavily phosphorylated, the functional impact of most individual sites is undefined. Here, we show that inhibition of CK2-mediated occludin S408 phosphorylation elevates transepithelial resistance by reducing paracellular cation flux. This regulation requires occludin, claudin-1, claudin-2, and ZO-1. S408 dephosphorylation reduces occludin exchange, but increases exchange of ZO-1, claudin-1, and claudin-2, thereby causing the mobile fractions of these proteins to converge. Claudin-4 exchange is not affected. ZO-1 domains that mediate interactions with occludin and claudins are required for increases in claudin-2 exchange, suggesting assembly of a phosphorylation-sensitive protein complex. Consistent with this, binding of claudin-1 and claudin-2, but not claudin-4, to S408A occludin tail is increased relative to S408D. Finally, CK2 inhibition reversed IL-13–induced, claudin-2–dependent barrier loss. Thus, occludin S408 dephosphorylation regulates paracellular permeability by remodeling tight junction protein dynamic behavior and intermolecular interactions between occludin, ZO-1, and select claudins, and may have therapeutic potential in inflammation-associated barrier dysfunction.
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Affiliation(s)
- David R Raleigh
- Department of Pathology, The University of Chicago, Chicago, IL 60637, USA
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23
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Al-Sadi R, Khatib K, Guo S, Ye D, Youssef M, Ma T. Occludin regulates macromolecule flux across the intestinal epithelial tight junction barrier. Am J Physiol Gastrointest Liver Physiol 2011; 300:G1054-64. [PMID: 21415414 PMCID: PMC3119114 DOI: 10.1152/ajpgi.00055.2011] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Defective intestinal epithelial tight junction (TJ) barrier has been shown to be an important pathogenic factor contributing to the development of intestinal inflammation. The expression of occludin is markedly decreased in intestinal permeability disorders, including in Crohn's disease, ulcerative colitis, and celiac disease, suggesting that the decrease in occludin expression may play a role in the increase in intestinal permeability. The purpose of this study was to delineate the involvement of occludin in intestinal epithelial TJ barrier by selective knock down of occludin in in vitro (filter-grown Caco-2 monolayers) and in vivo (recycling perfusion of mouse intestine) intestinal epithelial models. Our results indicated that occludin small-interfering RNA (siRNA) transfection causes an increase in transepithelial flux of various-sized probes, including urea, mannitol, inulin, and dextran, across the Caco-2 monolayers, without affecting the transepithelial resistance. The increase in relative flux rate was progressively greater for larger-sized probes, indicating that occludin depletion has the greatest effect on the flux of large macromolecules. siRNA-induced knock down of occludin in mouse intestine in vivo also caused an increase in intestinal permeability to dextran but did not affect intestinal tissue transepithelial resistance. In conclusion, these results show for the first time that occludin depletion in intestinal epithelial cells in vitro and in vivo leads to a selective or preferential increase in macromolecule flux, suggesting that occludin plays a crucial role in the maintenance of TJ barrier through the large-channel TJ pathway, the pathway responsible for the macromolecule flux.
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Affiliation(s)
- Rana Al-Sadi
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and
| | - Khaldun Khatib
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and
| | - Shuhong Guo
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and
| | - Dongmei Ye
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and
| | - Moustafa Youssef
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and
| | - Thomas Ma
- 1Department of Internal Medicine, University of New Mexico, Albuquerque; and ,2Albuquerque Veterans Affairs Medical Center, Albuquerque, New Mexico
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24
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Claudins and tricellulin in fibrolamellar hepatocellular carcinoma. Virchows Arch 2011; 458:679-88. [DOI: 10.1007/s00428-011-1077-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 01/19/2023]
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25
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Abstract
Tight junctions of epithelial and endothelial cells form selective barriers that regulate paracellular transport of solutes, immune cells, and drugs. Tight junctions consist of proteins that physically "seal" the tight junction but also form channels that allow for permeation between the cells, resulting in epithelial surfaces of different tightness. The tight junction proteins occludin, tricellulin, and at least 24 members of the claudin family are characterized by four transmembranal domains and two extracellular loops that, like teeth of a zipper, contact the appropriate loops from opposing cell membranes. Tight junctions are regulated in their molecular composition, ultrastructure, and function by intracellular scaffolding proteins and the cytoskeleton; such regulation serves normal, physiologic adaptation but also occurs in numerous diseases.
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Affiliation(s)
- Jörg-Dieter Schulzke
- Department of General Medicine, Campus Benjamin Franklin, Freie Universität and Humboldt-Universität, Berlin, Germany
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